Flame retardant rayon incorporating bis-diphenyl phosphate derivative of polyalkylene glycols

ABSTRACT

BIS-DEPHENYL PHOSPHATE DERIVATIVES OF SPECIFIED ALKYLENE GLYCOLS ARE INCORPORATED INTO VISCOSE SOLUTIONS WHICH ARE THEN SPUN INTO FLAME RETARDANT RAYON.

Uniwd- Sta e Pam- 3,556,825 FLAME RETARDANT RAYON INCORPORATING BIS-DIPHENYL PHOSPHATE- DERIVATIVE 0F POLYALKYLENE GLYCOLS Charles A. Lynch, Severnalark, Md., assignor to FMC Corporation, Philadelphia, Pa., a corporation of Delaware No Drawing. Filed Oct. 20, 1969, Ser. No. 867,918 Int. Cl. C0811 21/20 U.S. Cl. 106-168 3 Claims ABSTRACT OF THE DISCLOSURE Bis-diphenyl phosphate derivatives of specified alkylene glycols are incorporated into viscose solutions which are then spun into flame retardant rayon.

It is desirable for many textile purposes to provide cellulose fibers and yarns having greatly decreased flammability. The production of rayon-which demonstrates acceptable flame-retardant properties for all textile requirements, using inexpensive and commercially suitable chemical flame-retardants, has not been satisfactorily accomplished to date.

The application'of variousorganic and inorganic fiame retardants to the surface of cellulose fibers and fabrics has not produced the desired result for a number of reasons. In many instances, the chemical flame-retardant is effectively removed when thefabric is washed with water or dry cleaned with solvents. Other flame-retardant chemicals which may be applied to the fabric surface and retained after washing are generally too costly. In other cases, the chemicals used may provide some lasting reduction in flammability but destroy fiber and fabric characteristics, such as tenacity, softness, whiteness and dyeability, which are desirable and necessary for textile applications.

In the manufacture of rayon by the viscose method, it has been proposed to add various flame-retardant chemicals to the viscose prior to spinning. This approach presents many additional problems because of the particular chemistry of the viscose process. Accordingly, the flameretardant must be stable and inert with respect to the highly alkaline viscose and also with respect to the acid regenerating bath into which the viscose is extruded. It must not be extracted during spinning and processing. Furthermore, the added material must not interfere with the spinning process, i.e., cause clogging of the spinnerets. The rayon produced from the flame-retardant containing viscose must not be degraded in any of its properties and must have a substantially reduced flammability.

It is an object of this invention to provide a flameretardant rayon fiber without appreciable degradation of any fiber properties.

It is a further object of this invention to provide a process for preparing a flame-retardant rayon fiber which retains substantially all of the properties of ordinary rayon.

These and other objects are achieved in accordance with this invention which comprises a regenerated cellulose filament having dispersed therein a flame-retardant amount of a compound having the following formula:

wherein R is an alkylene radical having 2 to 4 carbon atoms, x is an integer of from 1 to 3; when x is 1, R has at least 3 carbon atoms, and when x is 3, R has 2 carbon atoms.

Compounds meeting the above formulation include, for example, dipropylene glycolbis-(diphenyl phosphate), dibutylene glycol bis-(diphenyl phosphate), triethylene glycol' bis-(diphenyl phosphate), tripropylene glycol bis- (diphenyl phosphate), tetraethylene glycol bis-(diphenyl phosphate) and the like.

In some instances the flame retardant compounds will consist of mixtures wherein the alkylene glycol residue varies in molecular weight whereby the average molecular weight of the compounds will place them within the above description.

This invention also includes a method of preparing a flame-retardant filament or filaments wherein the above described flame-retardant. compound is incorporated in viscose, the mixture formed into one or more filaments and the filaments are coagulated and regenerated. The

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formed filaments are aftertreated using techniques well known in the rayon field to provide continuous filaments, fibers and yarn as well as staple fibers. The filamentary products are then used to prepare any known textile article in which flame retardancy is desirable.

The number of carbon atoms in the alkylene radical of the above described flame-retardant compounds appears to be related to theretention of these compounds in the filaments during the viscose spinning process, If there are less carbon atoms than prescribed, the compound is more water soluble and consequently not retained in an amount sufficient to provide suitable flame retardancy. On the other hand, if more than the prescribed number of carbon atoms are present in the alkylene radical the percent of phosphorus in the compound is reduced and flame retardancy is greatly impaired.

The flame-retardant compounds are water-insoluble viscous liquids and are dispersed in the regenerated cellulose filaments in amounts ranging from about 10 to 50%, preferably from about 15 to 35%, based on the weight of the cellulose in the filament. The compounds are advantageously injected into the viscose solution prior The following examples are set forth to demonstrate this invention.

EXAMPLE I Dipropylene glycol bis-(diphenyl phosphate) was injected into the viscose line-supplying the spinnerets for manufacturing rayon in a metered amount to provide a filament containing about 25% by weight of the flame-retardant compound based on the weight of the cellulose. This viscose was spun into a conventional aqueous acid spin bath. The resulting yarn was processed by passing it through a series of baths including water wash, desulfurization, bleaching, bleach acid, anti-chlor (Na S O and soft finish baths. The yarn was dried and collected.

A yarn flammability test was conducted with yarn produced as described above. The test consisted of first preparing a yarn bundle by wrapping the yarn around the closed fingers of an extended hand to produce a bundle of 6000 denier and then removing it from the hand. The yarn bundle is twisted five times and then doubled on itself to produce an integrated yarn bundle,

n a nea i ches Qns.. r1d- ...Q9Q sui r. aize.

The free ends of the yarn bundle are clamped in forceps, and the bundle, held in horizontal position, is passed through the tip of the flame of a Fisher burner in an oscillating motion at a rate of one pass per second. The burner flame is adjusted to a two inch height and a blue flame. The number of passes to induce flaming of the sample is determined. A control yarn bundle (yarn contains no flame-retardant) inflames'in 1.01 2 passes and flame-retardant yarns are classified for inflammability as follows:

1-2 passes-poor 3-4 passes--fair 5-6 passes-good 79 passesvery good to excellent 10 or more passesexcellent Polyethylene glycol (200 average M.W.) bis-(diphenyl phosphate) was injected into viscose and the viscose spun into yarn as described in Example I. The yarn was processed and tested for flame-retardancy as in Example I. Retention of the flame retardant in the yarn after spinning and processing was found to be 55% of the amount procedure with no evidence of afterglow.

It is expected that improvement in the flammability test would accompany higher amounts of the flame retardant in the filaments ofthe yarn.

:1. Regenerated cellulosefilaments and filamentary articles, said filaments having dispersed therein aflame retardant amounttof'a compound having the following m wherein R is an alky le'ne radical having from 2 to 4 carbon atorn'sj,=j-x is an integer of from 1' to-fiywhen x is 1 or 2, R has at least 3 carbon atoms, and when g; is 3, R has 2 carbon atoms. 2. The

O OCH u/ U ege'nerated' cellulose filaments of claim 1 containing from about 10 to of said compound based on the weight of the cellulose in the filament.

3. The regenerated cellulose filaments of claim 1 Wherein'R has 3 carbon atoms and x is 1.

7 References Cited p V UNITED STATES PATENTS 3,092,651 6/1963v Friedman 106l77 MORRIS LIEBMAN, Primary Examiner T. MORRIS, Assistant Examiner U.S. Cl. X.R. 

